Presidential conventions are supposed to be an extended advertisement for the party’s standard-bearer, a finely scripted effort to cast the candidate in the best possible light. So it’s hard to see the rationale behind the Obama administration’s decision this week to showcase President Jimmy Carter – by common consent one of the worst if not the worst president in American history – in a prime-time video speaking spot at next month’s convention.

Most obviously, the inclusion of the outspokenly anti-Israel ex-president, whose contributions to Middle East peace include denouncing Israel as an “apartheid state” and making repeated overtures to anti-Israel terror groups like Hamas, highlights Obama’s frayed relationship with the Jewish state. From his famously frigid relationship with Prime Minister Benjamin Netanyahu, to his misguided call for Israel to return to pre-1967 borders, to his public rebuffs of Israeli appeals for a more robust response to Iran’s steadily progressing nuclear program, to his refusal to recognize Jerusalem as Israel’s rightful capital, Obama has consistently found himself on the wrong side of issues important to Israel and her supporters in the Jewish community. Indeed, pro-Israel advocates and activists have long suggested that Obama might be the president most hostile to Israel since Carter.

Carter’s appearance at the Democratic Convention can only further cement that dubious connection. There aren’t many issues that can bring the Republican Jewish Coalition and the National Jewish Democratic Council together, but this seems to be one of them. Both groups assailed Carter’s speaking role, with NJDC president David Harris writing:

“When it comes to Israel and the Middle East, President Carter has unfortunately embarrassed himself — as his analysis and commentary has been stubbornly wrong, harmful to the peace process, and getting worse all the time.”

The anti-Carter backlash could spell trouble for Obama, whose support is down among Jewish voters. After winning between 74 and 78 percent of the Jewish vote in 2008, the president is now backed by a still-dominant but notably diminished 64 percent of registered Jewish voters. Apparently recognizing that this could be an electoral liability, particularly in swing states with high-concentrations of Jewish voters like Florida, the Obama administration has recently embarked on a charm offensive aimed at Jewish voters, stressing its defensive ties with Israel and talking tough on Iran. But if offering coveted convention airtime to one of Israel’s most prominent public foes doesn’t entirely discredit that campaign, at a minimum it does not aid it. His political toxicity is surely one reason why Carter was a notable absentee from the 2008 Democratic Convention.

Israel isn’t the only issue on which Carter could be a liability. From a marketing perspective, it’s hard to conceive what political genius thought it would be wise to present a president beset by sluggish economic growth and the prospect of a one-term presidency alongside a failed one-term president whose downfall was economic malaise. After all, like Carter, Obama struggles from the perception that he can do little to revive economic prosperity, and the Romney campaign has had a field day paralleling the dim economic realities of Carter’s tenure to the country’s current woes. Nominating conventions are symbolic affairs, but presumably this is the kind of symbolism that the Obama campaign would wish to avoid.

The Carter comparison is actually more devastating than it may appear because by many measures Carter’s was the more successful presidency. As George Mason University’s Veronique de Rugy points out, a survey of job gains under 12 recent presidents shows that Obama is dead last in job creation. Far more jobs were lost than gained under Obama, and there are now 300,000 fewer Americans in the workforce than when Obama assumed office. By that standard, Obama would need the economy to generate 2.1 million new jobs every month until January 2013 just to match Carter’s economic record. In other words, Barack Obama isn’t Jimmy Carter — he’s worse.

As a historical matter, there are many similarities between Jimmy Carter and Barack Obama. Both were politically inexperienced candidates who proved ill-equipped for the presidency. Both had grand visions of governance that floundered amid poor stewardship of the economy. The trouble for Obama is that those similarities are not exactly ringing endorsements for a second term, and so it’s all the more curious that they will be on such prominent display as the president officially kicks off his reelection bid.